🔖 chore: number the legacy-decorator line 0.1.x, not 1.x

Nothing has been published, so a 1.0.0/2.0.0 split claimed a stability and a
history that do not exist. Staying on 0.x says what is true: the API may still
move. Under semver a breaking change is then a minor bump, which is exactly the
relationship between the two lines — 0.1.x keeps legacy experimentalDecorators,
0.2.x moves to TC39 standard decorators.

Branch renamed 1.x -> 0.1.x to match, along with its CI trigger and the
maintenance-line notice in the README.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SAcqrz3FcadkYr3xG32CjK

.github/workflows/ci.yml

@@ -2,9 +2,9 @@ name: CI
 
 on:
   push:
-    branches: [ main, develop, 1.x ]
+    branches: [ main, develop, 0.1.x ]
   pull_request:
-    branches: [ main, develop, 1.x ]
+    branches: [ main, develop, 0.1.x ]
 
 jobs:
   verify: